The present invention relates to industrial robots and was conceived in particular for the possible application of robots with a portable terminal associated therewith and designed to communicate in wireless mode with the robot control unit.
“Wireless” refers here to a communication involving a wireless communication of signals by means of electromagnetic waves, preferably by radio-frequency but possibly also by means of ultrasounds or infrared radiations or radiations in another frequency field.
Programming a robot basically means teaching said robot the trajectory which a point of its manipulator should repeat automatically during normal operating steps in order to execute a given operation. A robot can thus operate at least in an automatic and in a manual mode, which can usually be selected on the robot control unit. When manual mode is selected, for instance for programming or “teaching” a robot, the respective manipulator can be handled through instructions sent by a portable terminal; conversely, when automatic operation mode is selected, the motion of the manipulator is subject only to the control unit.
Most of the programming time is for manually controlling the robot, so as to identify the optimal points of the motion trajectories of the manipulator and store the coordinates thereof. To this purpose the aforesaid portable programming terminal is used, also known as teach pendant, which is operatively connected to the robot control unit and typically comprises a display and a series of pushbuttons used for programming and manually controlling the robot. The teach pendant can also be used for monitoring the robot program, for checking machine statuses, for modifying certain program parameters and so on.
In some solutions the terminal is connected to the control unit by means of a cable having such a length as to enable the operator to move near the working area of the manipulator and accurately check related points and trajectories. The aforesaid cable enables a limited controllability for the operator in his/her programming activity, since s/he should move continuously near the manipulator; another drawback consists in that the cable can get caught or entangled with other cables and should thus be freed. Moreover, the cable is subject to wear and tear and damages and therefore needs to be repaired or replaced. In order to solve such drawbacks it has been suggested to operatively connect the portable terminal to the control unit in wireless mode.
The operating environment in which a robot performs its functions, known as “cell”, has different configurations depending on the system layout and can contain one manipulator or more manipulators operating coordinately, each manipulator being equipped with its control unit. The use of wireless data exchange technology has a further advantage consisting in that one teach pendant can be used for controlling in manual mode each of the robots of a cell independently so as to program the latter. However, when one of the robots of a cell has to be placed under the manual control of a wireless teach pendant, it is extremely important to establish a definite univocal connection between the teach pendant and the robot to be controlled, so as to avoid possible dangers for the programming operator.
WO 02/078913 describes a system comprising a plurality of robots and a terminal that can communicate with a given robot of said plurality; to this purpose, the control unit of each robot is equipped with a stop pushbutton configured as a removable module, and the terminal is designed to receive said module in a suitable seat. The module comprises memory means containing a code identifying the related control unit; on the other side, the terminal comprises means for reading from said memory means of the module the code identifying the control unit. Knowing said code, the terminal can communicate only with the unit from which the module has been taken, so as to control manually the related manipulator.
The solution mentioned above complicates to a certain extent the implementation of the portable terminal, which should be equipped with a suitable seat and with related means of physical interconnection for the removable module; removable modules are further subject to frequent handlings, which might engender confusions as well as damages and a rapid wear and tear of their contacts, with subsequent risks of bad working.